Co-composting and vermicomposting of coal fly-ash with press mud: Changes in nutrients, micro-nutrients and enzyme activities

The present study was designed to determine the effect of vermicomposting on physicochemical properties, nutrient status and heavy metal concentration of buffalo dung, fly ash and press mud. Different ratios of buffalo dung, fly ash and press mud mixtures were used with without Eisenia fetida in this study. Vermicomposting of different feedstock mixtures for 90 days leads to significant reduction in pH, TOC, CN ratio and augmentation of plant nutrients such as sodium, potassium, phosphorous and calcium. Enzymatic activities (Dehydrogenase, urease, and phosphatase) were found elevated in the vermicompost feedstocks on day-30 followed by reduction up to 90 days. Moreover, the vermicomposting approach significantly reduced the heavy metals (Cu, Zn, Pb, Cr, Co, Cd, and As) in the feedstocks. It was found that an appropriate amount of buffalo dung, press mud, and fly ash favors the reproduction and growth of earthworms. The study results further supported the germination index on tomato plant seeds (Solanum lycopersicum). The results suggested that vermicomposting of press mud and fly ash with Eisenia fetida increased the nutrition content in a short amount of time. (C) 2020 Elsevier B.V. All rights reserved.